Edit: Since some people can't understand that this is a theory I am now putting in big letters:
THIS IS JUST A THEORY
Definition of Theory - SPECULATION(definition - to THEORIZE)
Edit: This pic of MAWJailer is confirmed to be The Jailer.
So with the datamining started, there are models for the Jailer and the Arbiter. The Jailer is missing his heart or power core which the Arbiter is in possession of. I believe that the Arbiter is the usurper and that the Jailer or whatever his true name is, is the true ruler of the Shadowlands. Here is a pic of the Jailer. The Arbiter isn't up yet but I saw it on the wowhead stream and she definitely has his heart/power core. I'll update the post with a pic of her when she's up.